(1) Field of the Invention
Disclosed is a polycrystalline metal oxide, methods of manufacture thereof, and articles comprising the same.
(2) Description of the Related Art
Lithium nickel oxide (LiNiO2) materials having a layered structure are desirable as lithium battery cathode materials because they generally provide lower cost, higher capacity, and higher rate capability than lithium cobalt oxide. However, pure LiNiO2 materials exhibit poor electrochemical stability and cycling performance. It has been found that by substituting varying amounts of other metals for some or much of the Ni in LiNiO2, some of the capacity and cost benefits of LiNiO2 can be obtained with improved electrochemical cycling stability.
Accordingly, a wide variety of layered-structure lithium nickel oxides, wherein a portion of the Ni has been substituted by another metal, have been developed. In particular, cobalt (Co) incorporation is found to enhance electrochemical cycling stability, and is readily achieved because of the favorable solid-state solution interaction of lithium cobalt oxide (LiCoO2) with LiNiO2. However, Co is more costly than nickel (Ni), and Co incorporation in LiNiO2 generally results in some diminution of the high capacity and rate capability provided by LiNiO2. Therefore it would be desirable to use only as much Co as is required to confer sufficient stability to a LiNiO2 to provide a lower cost material that provides more of the desirable properties of LiNiO2. Thus there remains a need for a lower cost lithium battery cathode material that provides the desirable properties of LiNiO2 at lower cost.